Eukaryote DNA maintenance systems are important in the repair of radiation and chemical damage, in recombination, and probably in normal DNA and RNA synthesis. The overall aim of this research is to investigate the variety and chemical bases of such systems in the fungus Neurospora crassa. DNA polymerase is an extremely important enzyme in bacterial DNA repair. We plan to investigate the role of this enzyme in the repair of DNA damage in Neurospora. After partial purification and separation of the enzymes present, three types of experiments will be run: 1) all the Neurospora UV-sensitive mutants will be examined for the presence of all the activities, 2) mutants whose UV sensitivity is inherited cytoplasmically will be isolated and examined for DNA polymerase activity since loss of a mitochondrial DNA polymerase activity may be important in cytoplasmic sensitivity, and 3) the possibility that a repair polymerase can be induced by treatments that damage DNA will be examined. If a repair DNA polymerase can be detected, its properties will be examined further.